Building construction



Dec. w. w. MACFARREN 2,103,359

BUILDING. CONSTRUCTION s Sheets-Sheet 1 Filed July 25, 1936 FIG.

INVENI'OR.

Dec. 28, 1937. w.'w; MACFARREN 2,103,359

7 BUILDING CONSTRUCT IDN Filed July 25, 1936 s Sheets-Sheet 2 INVENT OR.

' wwnmw,

Dec. 28, 1937..

w. w. MACFARREN 3,859

BUILDING CONSTRUCTION Filed July 25, 1936 a Sheets-Sheet s INVENTOR.

I/ I 3 A. R

Patented Dec. 28, 1937 UNITED STATES PATENT TQFFICE Claims.

My invention relates tobullding construction and more particularly toroofs, and is particularly well adapted 'fordwelling houses, bungalows,and other small buildings. Certain features of the construction however,are also adapted for use in large mill and manufacturing buildings, aswill appear later. V

Inthe drawings: I

Fig; 1 is a skeleton plan of a rectangular roof frame. according to myinvention...

' Fig. 2 is an elevation of the same, including the outside supporting,orwall columns.

Fig. 3.is a floor plan of a circular bungalow.

Fig. 4 is a floor plan of an elliptical bungalow.

Fig. 5 a diagrammatic elevation of a mill building. 1 I Fig. 6 is adiagram of some catenary curves.

Fig. 7 is a diagrammatic cross section on the line I--I of'Fig. 1. p N

Fig. 8 is an enlarged cross section through the outsidewall of anyfigure. I

Fig. 9 is an elevation of a portion of a corner outside wall column.

Fig. 10 is a cross section of a latticed welded floor beam. r

Fig. 11 is a horizontal cross section of, a corner outside wall column.V f

Fig. 12 is a horizontal cross section of am outside wall column. v a vFig. 13 is a horizontal cross section of an inside wall column.

Fig. 14 is an elevation of the circular bungalow of Fig. 3.

Fig. 15 is a diagrammatic side elevation of a a stand- 'mill building.

Fig. 16 is a diagrammatic end elevation of the same.

If the house is to have a cellar, thesame may be constructed in anysuitable way. If not, the preferred construction isa concrete foundationwall and a concrete floor slab, both to be suitably reinforced and tiedtogether. .On 'top of a the walls there is laid a steel bar or. channelI,

secured to the walls by suitable foundation bolts (not shown).

Referring to Fig. 8, the base channel I is laid back up, and may belevelled and grouted underneath. On top of the channel I there arespaced wall columns 3 which may be secured to the channel I by footbolts 4, which mayhave their heads spot Welded'to' the underside of thechannel.

When the concrete foundation has set, the base channels I may be set inplace, levelled, and bolted down. Then, starting at any desired point, awall column 3 may be set up and bolted to the and holds the upper endsof the wall columns 3 in line. It-consists of an outside member H which10 I prefer to form of steel pipe of suitable size,an inner member l9which'rests on the column top channels 6, and for which a rolled angleis a convenient section,'and a number of flat steel latticebars 20arrangedtobrace'the members l5 l8 and I9 together. The member I iswelded to theouter ends of the various channels 8, and the member ID iswelded to their inner ends to formatruss.

.Themembers l8 and Mean be made in con- :0 venient lengths and weldedend to end. If the truss ll is fabricated in the shop it can be made inabout 10 sections for the floor plans of Figs. 1 to'4. and if made inthe field it can be made of any convenient lengthsot material.

, When the truss I 'I is welded to the tops of all the wall columns 3,the bases of these columns can then be welded to the base channel I. Atthis point we have arigid steel structure to the eaves, and with thewall slabs i5 loosely in place.

In the design shown in Figs. 2 and 7 the eight central columns 26 carry"practically the entire weight of the roof if the same is formed by apreferred method to be described later, and these columns and theirfoundations may be designed accordingly. To show the flexibility of thesys-'- term I have shown in Figs. 3 and 4 other floor plans using thesame outer walls and wall columns as shown in Fig. 2.

One of the main features of the present invention is the use of a roofbuilt on the contour of a catenary curve.

According to the books "the'catenary is the curve assumed by a perfectly'fiexible cord when its ends are fastened at twopoints. the weight of aunit length '0! the cord being constant"-- 1. e. uniform.

Fig. 6 shows three separate catenary curves (approximated by circulararcs) all assumed to be supported from the common points A and B. Theuppercurve A C" B is shallow and similar to the curve used in suspensionbridges. The lower curve A C B is a deep one similar to that used forsuspended coal bunkers. The intermediatecurve A C D B is one suitablefor the roofs of small buildings.

It will be noted that in any of these curves, the stresses at the pointsC, C, or C" are horizontal. In the curve A C D B, if a support be placedat the point C, and one at the point D, the portions A C and D B may beeliminated, and only the portion C D used for the roof in hand. Thisportion of the curve is the one used for the rafters shown in Fig. '1.

All the points of the catenary curve may be figured mathematically,including the stresses for assumed loads, butthe formula is complex, andfor all practical purposes there is an easier method. Considering oneside of Fig. 7, the roof has a rise of one half its span.

In Fig. 6 it will be evident that if the points C and D represent theposition of the cave and ridge of a proposed roof to a full size scale,a cord may be stretched over them tightly in a substantially straightline as shown dotted. If the tension of the cord is gradually reduced,the cord will assume a variety of curves, each one of them being a truecatenary, until a curve such as C E D is reached. However curves muchbelow the curve C D are not suitablefor drainage. The desired curve toplease the eye may be thus selected for small roofs in a few minutes.

Now it is also necessary to know the stress in the cord in order todesign the rafters or trusses. This may all be calculated by abstrusemathematical formulae but here again a simple method is available. Inorder to obtain the tension in any given catenary, a chain of knownweight per foot may be stretched to the desired curve, and its tensionmeasured by a spring balance or other means, from which the tension dueto any uniform load may be easily calculated.

However the loads on a roof are not uniform.

'- The roof must be strong enough to support I in any other type ofroof. In the roof of Fig.

7 the snow will probably lie deepest at the lower portion of the curve,and the wind pressure will be greatest at the upper portion of thecurve.

In order to provide for these varying conditions I prefer to make use ofa pair of catenary tension members one above the other, and connected bybracing one to the other. thus forming a trussed rafter or small rooftruss.

In Fig. 7 the upper catenary tension member 21 may pass over a ridgepole or pipe 90, and be welded at each of its ends to one of the pipesIS on either side of the house, and also to the ridge pole 30. The lowercatenary tension member 28 may also have its ends welded to the sidepipes l8, and its middle portion supported by a pair of ridge poles 3i,and the three ridge poles 30 and 3| may be connected by welded latticebars to form a triangular truss. This construction is merelyillustrative of a variety of suitable details.

The lattice bars 29 may have their ends welded to each other and to themembers 21 and 28. The assembly of the members 21, 28, and 29 will bemuch lighter for an equal span and equal loads than a beam, because theprincipal or dead load stresses in the members 21 and 28 are normallypure tension, as compared to the flexural stresses in a beam.

Either the members 21 and 28 may be of equal section to divide the load,or the upper member 21 may be designed to carry the full load, and thelower member 28 may be made only strong enough to avoid distortion ofthe upper member 21 from the catenary curve when the rafter is subjectedto uneven loading. As

- long as the loading is uniform and the upper member 21 keeps its truecatenary contour the stresses therein are purely tension.

To support the ridge poles 30 and 3|, I provide a series of A frames 32resting on the eight central columns 26 of Fig. 7, and on the endoutside wall columns 3 in line therewith, if 'the roof slopes only tothe side walls.

, If the roof slopes both to the ends and sides of the house, I provideadditional corner ridge poles 34, 35, 36, and 31 as indicated in Fig. 1,and which are supported at their outer ends by the pipes l3, and attheir inner ends by one end of the ridge pole 30. Since this design isfor a welded assembly, I prefer to use common steel pipe of suitablesizes for the members I8, 30, 3|, 34, 35, 36, and 31, as affording easyconnections for the flat bar members 21 and 28, and being easy to weldto each other.

In order that each rafter may have the catenary form, the members 34,35, 3B, and 31 must be bent to a curve which will be the intersection ofthe side catenary roof slope and the end catenary roof slope, which maybe duplicate or different curves, and each member 34, 35, 3B, and 31 maybe built as a truss similar tothe members 21 and 23.

As the rafters in this case are of different lengths, the constructionwill naturally be more expensive, and it is for the'builder to determinewhether the enhanced appearance is worth the additional expense, Just aswith a roof framed of wood.

It is also to be noted that if the full length rafters 40 of Fig. 1, arebent to a true catenary, the shorter rafters may not be a true catenary,but they will be close to one, and this is of no particular importance,as these rafters are trussed, and carry a lesser load than the fulllength rafters.

The assembled rafters of Fig. 7 may be designated as a whole by thenumeral 40, and may be spaced from two to four feet apart depending onthe type of sheathing used, and various building codes in cities. Assheathing to span the spaces between the rafters 40, wood, metal, orvarious composite materials may be used.

For this purpose I prefer steel as being both light and strong, andbecause of its stiffness corrugated steel is ideal for the purpose. Suchsheets are specifically designed for roofing, to be laid on spacedpurllns with their corrugations running down the roof slope. When soplaced and lapped they are rain proof. However, for the presentinvention, the sheets are placed with their corrugations runninghorizontally, or at right angles to the rafters 40. In such positionthey span the spaces between the rafters 40 efiiciently, and beingflexible parallel to their corrugations, they may be readily bent to theroof curve.

The sheets 38, so laid may be bolted, clipped, or spot welded to the toprafter member 21. Above the sheets 38 I prefer to use a sheet .coppercover 39, which may be fastened to the sheets 38 by small rivets. Thecombination of the steel corrugated sheathing and the sheet copper covergives a roof which is light, strong, water, wind, and fire proof, verydurable, and of good appearance.

It is obvious however that practically any usual type of roofingmaterials may be employed; as

. positions are .notsumciently "fire resistant, and

tional in shape, theplans seem to applicant to shingles, tile, slate, orvarious, composition roofings. Woodshinglesandthe varioustarred com- 4slate or tile cause needless weight ata point where it does the mostdamage during an earthquake.

' 'At 14 I show braces from thetop of the out- 7 side' walls to acentral pointof certain of the rafters 140. All these bracesmay be orflat steel bars or light 'angleswithwelded connections, and

may be applied wherever needed almost as easily as a wooden brace may'becut and ,nailed.

The whole oi the housema'y be provided with a ceiling at'the level ofthe eavesgor certain rooms may be celled at. the rafters. For, the firstcaseI prefer to'us'e a suspended'ceiling constructed 'as follows: A

Theangle i9 extends entirely aroundjthe house.

The interior partitions may be built to' an equal height and capped'witha flat bar welded to, the

topsof the interior columnslor studs. Upon these members and weldedthereto, there may be placed a series of small flat bars, say x 1 insection or evensmaller, andspaced about two feet apart. Instead of fiatbars, the members 43 may be small angles or channels, or the upper andlower members 43 may beany desiredc'omblnation ofiilat bars, angles, orchannels. 7

In the design of Fig. l'the'se bars should be set diagonally, or at anangle of 45 degrees with l-he'outer walls, and all the bars should bewelded to each other at their various intersections, thus forming a netor mesh similar to wire netting.

the rafters 40.

To support these bars between the partitions I "providevertical tires 4|of fiat steel, say x in section, the upper ends of. these ties beingwelded to the lower member" of therafters l0, and their lower ends beingwelded to the upper sides o'f the ceiling bars 43J'There maybe a tie 44at each intersection or the bars 43, and the ties may be" inclined tomeet'the rafters 4!! where necessary. v

If a plasteredceiling is desired, metal lath may be wired, clipped, orwelded to the bars 43 to receive the plaster. I prefer however tousesome form of wall board or asbestos sheeting, which may be fasteneddirectly to "the under sides of the In certain cases it may be desired,for architectural effect,'to place the ceiling just under It will-benoted that sincethe tensilestresses in the catenary' rafters arepractically-horizontal at the eaves, substantially the whole weight ofthe roof of Figs. 1 and 7 is-carried bythe central inside wall columns26,-which with their foundations must be designed accordingly.

The rectangular houses 'of Figs. 1, 2, 3, and 4 have iii-panels of 4 ft.each,*or a-wall periphery of 144 linealfeet and the'enelosed gross areawith a wall 6 thick is 27.51: 43.5 or 1196sq."it.

The elliptical houseof Fig. 3 may also have 36 panels of 4 ft. and'thesame wall peripherary of 144 ft., but the gross enclosed area-here isapproximately 1560 sq. ft. passing; that it is not necessary "to use, atrue ellipse, as a close approximation may beobtained by the use of fourconnected circular arcs; which areeasier to layout.

The circular house of Fig. "G'may also have 36.

panels of 4' ft. and a wall peripheryof 1.44 ft., but here thegrossenclosed area is 1626 sq. ft.

with 6" walls, or .a gain of 430m. it. in usablearea with the sameexpense for the enclosing wall.

This isa g'ainof over' 36%.

a While the rooms of Figs. 3 and 4 are unconvenacross the building.

It mayv benoted in show equal utility and convenience, and a distinctefficiency will occur in the rafters becausethey are not parallel. Thecorrugated sheathing 38, and the copper covering 39 will also be cut' tosome waste of material. i

Let us now pass from the details or bungalows featuresofQthis'inVentiOn, viz.the c'atenary roof.

The simplest'form of catenary roof is a metal sheetsuspendedby two ofits ends or edges to hang in a catenary curve, and combined withsimilarsheets to cover a desired area; Such a construction is ,indicateddiagrammatically in Figs. 15 and 16, inlwhich such sheets are1sup portedbetween adjacent rbof trusses 59, Iorming -a flat shallow trough betweenthe trusses "which should be slopedtoward the outer walls of thebuilding for drainage. In sites where there were no winds, such anarrangement might be suitable, without any bracing forthe roofsheets-60. But such'lo'cations are rare.

Now ifat intervalsol three toiive feet, light flat bars 6| aresuspendedunder the sheets 60 and in parallel relation thereto, such barsmay be connected directly to the sheets Giiby welded lattice bars 62, tostiffen the sheets.

tion could be used with bays of say 20 feeigand using standard or usualcolumns and roof trusses;

the usual purli ns and corrugated sheet roofing being eliminated, andreplacediby the suspended catenaryroof sheets Gland the bracing members6] and 82.

4 m t 01' this kindwould certainly lighter.

tha'nthe usual construction of purlins and corrugated sheets, as thepurlinsare necessarily strong enough toresist fiexure, as are also the.corrugated sheets This is'the prime reason: for corrugating them. I: theother hand the catenary sheets Gil and the brace bars. flare inpuretension when under uniform loads. e

A further application" of this'principle for buildings of wide span isindicated i Fl .;17, which will in a sense eliminate roof trusses. Inthis case th-usualsteel building columns 63 could be used, having acontinuousbeam or truss 64 running along their tops. This member wouldtake both. vertical, and horizontal. loads Between each pair of oppositecolumns 63, ajhorizoritalcompression member, isplaced, to span From theupper surfaces oi the opposite trusses 64, the roof .sheets 66 may bestretched, and between the roof sheets 66 and each of manta. zontalcompression members 65', spaced verticalties 61 may be placed. These mayeither be threaded rods with nuts, or welded ties as previouslydescribed. I

This construction formsla truss in which the top member is in tensionand the bottom member in compression, being the exact reverse of usualpractice. In this case also, the weight of the to a wider consideraionofone-of the principal" In thisway a standard m building construcmembers65 and 61 is supported by the roof sheets 66, and the tension of thesheets 66 is balanced would not be a true catenary, but could be made toapproach this curve to any desired degree by closer spacing of the tiebars 61, or by branching them as indicated at 6!. Such a roof beingfairly flat, would not be affected by ordinary winds, and snow loadswould be fairly uniform. It is thought that roof spans of 100 feet ormore may be practical with this system, and that proper calculationswill show a considerable economy in material.

In roofs of the type shown inFlgs. 5, 15 and 16, the most practicablematerial for the roof sheets 60 and 66 is steel. The sheets could haveadjacent edges lapped'and welded. They should be of copper alloy steel,or othernon-corrosive metal. For the cover sheets 39 of Fig. 7' coppersheets are the best, but very likely a copper alloy or brass sheet wouldbe good enough and cheaper.

To summarize, a roof employing the catenary curve, with the sustainingmembers in pure tension under uniformly distributed loads, may fallunder any one of the following five general classes:

-1. The roof may consist of a single sheet of metal or other material,stretched in a catenary curve, and being self supporting under its owntension.

2. The roof may consist of a metal sheet'as above, and having attachedspaced catenary braces to take eccentric or non-uniform loads.

3. Instead of the covering sheet being selfsupporting as in 1 and 2, thesame may be supported on catenary rafters or tension members, withinterposed sheathing, and such rafters may either have sufficientstiffness in themselves, or be braced or trussed, to carry non-uniformloads.

4. The roofcovering sheet may be a composite member such as a concreteslab with steel reinforcing bars, the slab being laid in a catenarycurve with the reinforcing bars adapted to take the tensile stressesproduced by the weight of the slab. Various other forms of compositeroof covering may be used, such as'asbestos sheets containing steel wiremesh. The essential requirement is that the'roof covering be wind andwater tight, and that it be laid in a catenary curve or onesubstantially similar thereto, and that the covering sheet, or itssupports possess sufficient strength for safety.

5. The roof of a large building may be subdivided into sections, ofwhich each section is a separate unit partaking of the characteristicsof some of the above classifications, or combined with older forms.

Having now set forth my invention in various preferred forms, and insuch detail that those skilled in the various related arts may apply it,I claim as my invention:

1. In a building structure, supporting members such as columns or walls,a roof comprising a sheet of material adapted to resist tensilestresses, the said sheet being suspended in the form of a catenarycurve, and continuous bracing means extending from one sheet support tothe other, to prevent distortion from the said catenary curve.

2. In a building structure, supporting members such as columns or'walls,roof trusses supported thereby, a roof comprising a sheet of ma-- terialadapted to resist tensile stresses, the said sheet being suspended insections between adjacent roof trusses in the form of a catenary curve,

and a continuous lattice for bracing the said roof sheet againstdistortion from the said curve.

3. In a building structure, two lines of parallel building columns, atruss extending along the tops of the said columns and adapted to resistboth horizontal and vertical stresses, roof sheets adapted to resisttensile stresses stretched across the building and secured to the saidtrusses, compression members extending across the building below thesaid roof sheets and between opposite building columns, and tie rodsconnecting the said roof sheets and the said compression members tosupport the latter.

4. In a building structure, supporting members such as columns or walls,rafters spanning the said supports, each of the said rafters comprisinga pair of tension members spaced apart. vertically, and curved to thecontour of a catenary, bracing members connecting the said catenarytension members to obtain rigidity, and a roof covering supporteddirectly on the said rafters.

5. A steel frame for a building structure, comprising in combinationoutside wall columns, a ridge pole, catenary rafters supported by theabove two elements, the said rafters each being composed of two flatbars in substantially parallel relation and connected by lattice bars,and corrugated steel sheathing secured to the said rafters with itscorrugations set horizontally to support a weatherproof covering.

6. A steel frame for a building structure, comprising in combinationoutside wall columns set in a continuous curve, inside wall columns insupporting relation to the roof, a continuous truss supported by thesaid outside wall columns, and adapted to resist both horizontal andvertical stresses, and a roof carried by said inside wall columnsand bysaid truss and which in vertical section has the contour of a catenarycurve, and in which the supporting members thereof are in pure tensionunder uniform loads due to their catenary contour.

7. In a building structure, roof supporting members, transverse rooftrusses supported thereby, a roof sloping both ways from a ridgeextending lengthwise of the structure toward the sides thereof, the saidroof comprising sheet material adapted to resist tensile stresses, andhung in sections secured to adjacent roof trusses, each section beinghung in the form of a catenary curve extending from one roof truss tothe next, the upper surfaces of the said roof sections forming wideshallow troughs extending across one half the width of the structure andthe said sheet material being curved in one direction only.

8. In a building structure, supporting members, a horizontal truss orplate extending along the tops of certain of the said members, a ridgepole supported by certain of said members, catenaryrafters spanning fromthe said ridge pole to the said plate, a roof covering over the saidrafters and supported thereby, a series of criss-cross bracing barsextending horizontally to cover the area enclosed by the said plate, andsecured to the said plate to brace it against the pull of the catenaryrafters, and tie bars connecting the said rafters and the said crossbars to support the latter.

9. A fabricated steel rafter for building structures, comprising incombination an upper member in the form of a flat bar, and which is bentto form a catenary curve, a lower member also in the form of a flat bar,and bent to a catenary curve substantially parallel to the curve of theupper member, and flat lattice bars connecting the said upper and lowermembers to obtain rigidity.

10. A fabricated steel rafter for building structures, comprising incombination an upper member in the form of a flat bar, and which is bentto form a catenary curve, alower member also in the form of a flat bar,and bent to a catenary curve substantially parallel to the curve of theupper member, and flat lattice bars having their ends weldedrespectively to the said upper and lower members, and with theirrespective edges adjacent to the edgesof the said upper and lowermembers.

11. A fabricated steel rafter for building structures, comprising incombination an upper member in the form of a flat bar, and which is bentto form a catenary curve, a lower member also in the form of a flat bar,the same being bent to a catenary curve substantially parallel with thecurve of the upper member, and flat lattice bars connecting the saidupper and lower members to form a rigid structure, the said upper memberbeing proportioned to support all uniform loads, and the said lowermember being proportioned to take such eccentric loads as may reasonablybe expected to be placed on the roof.

12. A fabricated steel rafter for building structures, comprising anon-flexible bar having upper and lower flanges and a central portionconnecting the said flanges, the same being bent to of a triangle,lattice bars connecting each of the said members with two of the others,sup ports for the said ridge pole, and catenary rafters extending fromthe said ridge pole to an eave of the roof.

14. In a building structure, roof supporting members,

roof covering comprising sheet material adapted to resist tensilestresses, and hung on the said rafters in parallel catenary shapedtroughs extending from rafter to rafter, to cover the space below therafters.

15. In a building structure, roof supporting members, a ridge pole,straight parallel rafters extending from said ride pole to an eave ofthe roof, and being sloped for drainage, and a roof covering comprisingsheet material adapted to resist tensile stresses, and hung on the saidrafters in parallel catenary shaped troughs extending from rafter torafter, to cover the space below the rafters.

WALTER W. MACFARREN.

I straight parallel rafters supported thereby, and being sloped fordrainage, and a

